▎ 摘　　要

The redox, chemical and biochemical characteristics of molecular hydrogen (H-2) and hydrogen peroxide (H2O2) promise affordable, sustainable and environment-friendly solutions to some serious global challenges related to energy, environment and human health. However, the non-availability of a cheap, efficient and durable electrocatalysts continues to hamper the practical exploitation of H-2 and H2O2 as solution to these challenges. Herein, we present a simple strategy for the fabrication of Vitamin B-12 functionalized nitrogen-doped graphene (Vit.B-12-NGr) nanohybrid, as an electrochemically stable, reusable electrocatalyst with an excellent prospect for hydrogen evolution reaction (HER) and non-enzymatic electro-oxidative sensing of H2O2. For HER, the Vit.B-12-NGr nanohybrid displays onset potential of just -0.096 V vs. RHE, a low Tafel slope of ca. 60.35 mV/dec and an overpotential requirement of just -0.210 V for 10 mAcm(-2). Moreover, the Vit.B-12-NGr is demonstrated as a promising electrocatalytic surface for the electro-oxidative sensing of H2O2 with a sensitivity of 430 mu AmM-1 (8.775 mu AmM-1 cm(-2)) and a limit of detection as low as 20 nM. These HER and H2O2 sensing parameters displayed by Vit.B-12-NGr are either superior or comparable to those observed for the various recently reported state-of-the-art HER electrocatalysts and H2O2 sensors. (C) 2020 Elsevier Ltd. All rights reserved.